Bucket loader stops



July 24, 1962 R. J. BERNOTAS 3,045,843

BUCKET LOADER STOPS Filed Feb. 11, 1957 v IN VEN TOR.

flaw cZZZyzaKar BY ATTORNQ United States Patent 3,045,343 EUQKET LEADER S'EQPS Ralph J. Bernotas, South Euclid, flhio, assignor to General Motors Corporation, Detroit, Mich, a corporation of Deiaware Fiied Feb. 11, 1957, Ser. No. 639,409 4 (Iiaims. (Cl. 214-440) The present invention relates to loader mechanisms of the type comprising a vertically adjustable boom having one end pivotally connected to a vehicle or other support, a material handling device pivotally attached to the other end thereof, means for tilting the material handling device about its pivotal connection to the boom and yieldable stop means carried by the boom and engageable by the material handling device.

Loader mechanisms of the type described typically include either a rubber-tired or crawler track vehicle to which a vertically adjustable boom is pivotally connected at one end and to the other end of which a material handling device is pivotally mounted. Means are provided for reaction between the vehicle and the boom to vertically adjust the latter about its pivotal connection to the vehicle. In addition, a tilt linkage is mounted between the vehicle frame and the material handling device for controlling the position of the latter about its pivotal connection to the boom.

Such tilt linkages may be designed to automatically adjust the position of the material handling device relative to its supporting boom and the ground to maintain it in a non-spilling attitude relative to the latter. On the other hand, such tilt linkages may be manually controlled to provide this desired result. Irrespective of how the specific material handling device is tilted or pivoted relative to its supporting boom, it will be appreciated that in loader mechanisms of this type the material handling device will be pivoted forwardly closer to its supporting boom as the latter is raised vertically. Thus, since the dump angle of such a device is ordinarily limited by its abutment with a rigid stop on its supporting boom or associated structure, it will be appreciated that smaller dump angles will be obtainable as the bucket boom is adjusted upwardly.

in addition, such tilt linkages ordinarily include at least one link, which may be extensible or permanently rigid, which is pivotally connected to the material handling device at a point spaced from the pivotal connection of the latter to the supporting boom whereby, upon actuation of the tilt linkage, such a link will be operated to tilt the material handling device about its pivotal connection to the boom. A problem is therefore presented in preventing such a link from going over-center relative to the pivotal connection of the material handling device to its supporting boom, which would preclude returning the material handling device to its upright or carry position. Moreover, if such a tilt linkage includes a hydraulically actuated tilt jack, reverse pivoting of the material handling device from a dumping position may not be possible if the tilt jack is extended to a position in which it is incapable of applying the necessary leverage for such return pivoting.

In such mechanisms, it is also desirable to employ a stop means adapted to be repeatedly abutted forcibly by the material handling device as it is dumped. In the usual operation in which sticky materials are being transported, operators will actuate the tilt linkage to repeatedly rap the material handling device against such a stop to dislodge all the material contained therein. For the reasons aforementioned, such stops as heretofore employed become closer and closer to the material handling device as the supporting boom therefor is adjusted vertically upwardly. Consequently, the higher the boom arms are at the time that dumping of the material handling device is desired,

3,045,843 Patented July 24, 1962 the sooner such stops will be engaged by the pivoting material handling device, thereby reducing the dump angle obtainable at higher elevations of the supporting boom.

By utilizing the yieldable stop means of this invention with a loader vehicle or mechanism of the type disclosed, it is possible to avoid all of the disadvantages aforementioned while obtaining many advantages heretofore not known in the art. According to the present invention, yieldable stop means are mounted on the loader boom adjacent the pivotal connection of the latter to the pivotable material handling device carried thereby so that, as the material handling device is pivoted forwardly in the process of dumping material, it will engage such stop means. Thereafter, the tilt linkage for the material handling device may be repeatedly actuated in opposite directions to forcibly engage the material handling device with the yieldable stop means to dislodge all materials carried by such device.

According to this invention, such yieldable stop means may be further related to the tilt linkage, material handling device and supporting boom therefor to prevent disabiing of the tilt mechanism thereby insuring that it will be able to return the material handling device to an upright position after dumping. According to this feature of the invention, the yieldable stop means will function to provide a force in opposition to that of the tilt linkage to provide the impetus to return the material handling device from a dumping position to an upright position or, alternatively, may apply a force which progressively increases in opposition to the force supplied by the tilt linkage to prevent the latter from going over center as well as providing such an impetus.

Furthermore, the yieldable stop means of this invention is operable to give a larger dump angle at higher elevations of the material handling device supporting boom than heretofore possible. Thus, according to this invention, the yieldable stop means is so designed as to be progressively more compressible as the bucket supported booms are elevated, thereby insuring a large dump angle irrespective of the elevation of the boom.

More specifically, the present invention contemplates a variably yieldable or adjustable spring stop mounted on a supporting boom adjacent the pivotal connection of the latter to a material handling device which may be pivoted the-reabout into engagement with said stop under the control of a hydraulically actuated tilt linkage as is commonly used in this art. The position of this stop means is such relative to the pivotal connection of a material handling bucket to its supporting boom and to the geometry of the tilt linkage for the bucket as to insure that the tilt jack will be operable to return the material handling device to its normal upright position.

The yieldable stop means of this invention is also so related to the geometry of the loader mechanism as to permit yielding thereof to progressively greater amounts as the bucket booms are elevated, whereby dump angles are not reduced as much as in present loaders at higher elevations.

These and other features of this invention will appear more fully hereinafter as the description proceeds, and in which reference is made to the following drawing in which:

FIGURE 1 is a side elevation of a front end loader equipped with this invention;

FIGURE la is a fragmentary view, partly in section, showing a preferred form of the bucket loader stopv in more detail.

Referring now to the drawing, there is shown a vehicle 2 having an engine 4 positioned to the rear of a drivers compartment 6 and suitable transmission and drive means 8 to the rear wheels of the vehicle. Although a rubber-tired vehicle is shown, it will be understood as the description of the invention proceeds that it is immaterial whether such a loader mechanism is mounted on a rubber-tired vehicle of the type shown in the drawing, a crawler tractor, or even a stationary suport.

p A loader mechanism is indicated generally at and comprises a supporting boom arm 12 having its rearmost end pivotally mounted at 14 to the vehicle at a point forward of the drivers compartment, and which boom extends forwardly and downwardly and is pivotally connected at 16 to a material handling device 18 herein shown to be a bucket. It will, of course, be understood that there is a similar supporting boom arm 12 on the other side of the vehicle which is likewise pivotally connected to the vehicle 2 and bucket 18 on transverse axes coaxial with the pivotal connections 14 and 16 Hydraulically actuated lift jack 20 is pivotally connected at 22 to the vehicle and at 24 to each supporting boom arm 12 intermediate the length of the latter whereby, upon actuation of the jack 20 by a suitable hydraulic system, the two supporting boom arms 12 may be adjusted vertically.

A tilt linkage is associated with each boom arm 12 and, in each instance, comprises a tilt control link 26' pivotally connected at 28 to the vehicle at a point spaced forward of and below the pivot 14, and is pivoted at 30 to the upper end of an intermediate lever 32 which is pivotally connected to the boom arm 12 at 34. A hydraulically actuated tilt jack 36 comprises a cylinder 38 pivotally connected at 40 to the lower end of the intermediate lever 32 and has reciprocably disposed therein a piston to which one end of the piston rod 42 is attached, the other end of rod 42 being pivoted at 44 to the material handling bucket 18 at a point spaced above the pivotal connection 16 of the latter to the bucket supporting boom arms 12.

Although not necessarily required to practice the subject invention, it is preferable to construct the loader mechanism as aforedescribed having geometry which will provide an initial roll-back of the bucket 18 as the boom arms 12 are initially lifted from the full line position of the drawing, such roll-back being followed by automatic forward pivoting or tilting movement of the bucket relative to its pivotal connection 16 to the bucket supporting boom arms as the latter are lifted vertically through the positions shown in dotted lines. By utilizing the tilt linkage geometry as herein disclosed by way of example, it will be noted that the pivotal connection 34 of the intermediate lever to the boom describes one are about the pivot connection 14 of the supporting boom to the vehicle as the boom is lifted vertically. Furthermore, another are is described by the pivotal connection 30 of the tilt control link 26 to the intermediate lever about the pivotal connection 28 of the tilt control link to the vehicle. Because the tilt control link 26 is rigidly connected between the vehicle and the intermediate lever, it will be appreciated that it will function to pivot the intermediate lever to pivot the bucket as the arcs described between pivot points 30 and 34 move relative to each other. Using the geometry described in the drawing, the paths of these two pivot points are such as to provide the initial automatic roll-back and automatic adjustment forwardly of the bucket relative to its sup porting boom arms as aforedescribed. However, the present invention may be utilized with any type of geometry of tilt control linkage to provide automatic positioning of the attitude of the bucket relative to its supporing boom and the ground, or even with a tilt linkage which must be manually actuated to accomplish any tilting of the bucket. The yieldable stop of the present invention, which is to be described, may be used with any loader mechanism arrangement of this general type irrespective of the specific construction and geometry that it may employ.

At least one, but preferably both, of the supporting boom arms 12 have rigidly secured to the inner sides thereof a laterally inwardly projecting bracket 46 which slideably receives a bolt 48 having an enlarged head 50 at its forward end and, at its opposite end, a nut 52 to retain the bolt on the bracket. Preloaded spring 54 is coiled about the bolt and abuts the enlarged head 50 and forward face of the bracket 46 to continuously urge the bolt forwardly in the bracket as limited by abutment of the nut 52 with the bracket. A stop plate 56 is welded or otherwise secured to the bottom of the bucket 18 and is aligned with the spring stop mechanism so as to be able to engage the latter as the bucket is tilted forwardly about at its pivotal connection 16 to the bucket supporting boom arms 12.

In the first instance, it will be appreciated that the spring 54 may be of such strength as to provide an effective force against which the bucket 18 may be repeatedly projected by operation of the tilt linkage to dislodge material sticking in the bucket as the latter is dumped. Moreover, this yieldable stop means has at least two other primary functions; i.e., to prevent disabling of the tilt jack by reason of the latter going over-center in dumping the bucket, or at least to prevent it from extending to such an extent that it is incapable of applying the required leverage to retract the bucket to an upright position, and to provide a stop means which will not reduce too greatly the dump angle of the bucket as the bucket supporting arms are lifted upwardly.

In operation, the loader mechanism may be lifted vertically from the full line position shown in the drawing for dumping into the back of a truck or other conveyance. It may be desirable to dump the bucket when the boom arms are in an intermediate position in which the boom arms 12 extend substantially horizontally forwardly, or when the boom arms are in a high lift position. Such positions are indicated by the dotted line figures in the drawing, the tilt linkage having been operated to pivot the material handling bucket 18 to a dumping position. As aforedescribed, as the bucket supporting booms are lifted vertically upwardly from the full line position, the tilt linkage will automatically maintain the bucket 18 in a non-spilling attitude relative to the ground by progressively tilting it forwardly about its connection to the boom as the latter is raised upwardly. It will be quite clear, therefore, that the stop plate 56 will be nearer to the spring stop mechanism carried by the bucket supporting arm 12 at higher elevations thereof than when in a lower position. Thus, the enlarged head 50 of the yieldable spring stop means will be engaged sooner when the loader mechanism is in the high lift position than it will in a lower position such as the inter-medate poston. In other words, when the stop plate 56 first engages the enlarged head 50 of the spring stop means, the tilt jack 36 will have been extended a shorter distance in the high lift position than in the intermediate position and, consequently, if the stop were not yieldable the dump angle of the bucket would be less in the high lift position. However, a large dump angle is obtainable even in the high lift position by employing the yieldable stop means of this invention due to the fact that the coiled spring 54 will compress to a greater extent in the high lift position than in the lower positions.

It will be noted that in loader mechanism of this type, it is ordinarily necessary to arrange the tilt jack relative to the pivotal connection of the loader bucket to its supporting boom in such a manner as to preclude disabling of the tilt jack by reason of its going over-center in dumping the bucket, or extending to such an extent that it is incapable of operating in retraction to apply suflicient leverage to return the bucket to an upright or carry position. In other words, in loader mechanisms of this general type which are not equipped with the yieldable stop means of this invention, care must be taken in designing the apparatus so that the line of action of the tilt jack between its pivotal connections at 40 to the intermediate tilt lever and a 44 to the bucket does not pass through the pivotal connection 16 of the material handling bucket to the boom, since the bucket could then continue to swing forwardly clockwise as shown in the drawings. As a practical matter, there is a limit to the distance by which the line of action of the tilt jack 36 can approach the pivotal connection 16 and still be able to apply sufiicient leverage to the bucket to return it to its carry or upright position. If the jack is extended too far relative to the pivotal connection of the bucket to the boom, it will be incapable of applying this leverage unless it is made inordinately large in any specific linkage design.

To avoid this difficulty, the yieldable stop means of this invention is positioned on the supporting boom arms 12 so that the force of spring 54 acts at some preselected distance from the pivotal connection 16 of the bucket to the boom. The particular distance selected will depend upon the overall design of the loader linkage and, in particular, on the design of the tilt linkage and its connection to the bucket. Thus, in the intermediate position of the bucket booms as shown by the dotted lines in the drawing, the tilt jack center line at the time when the stop plate 56 engages the bolt head 50 will be in a particular position relative to the bucket pivotal connection 16 to the boom so that the spring 54 may be compressed a certain amount at stall-out of the tilt jack prior to the latter become disabled for retracting the bucket. Thereafter, the expansion of the spring 54 as the hydraulic system is actuated to retract the tilt jack is such as to provide the initial impetus to initiate such retraction to return the bucket to its normal postion. If the bucket supporting booms are lifted to the high lift position as shown in dotted lines in the drawing, the yieldable spring stop is compressed to a greater extent than in the lower intermediate position, but is still elfective at tilt jack stall-out to supply the initial impetus to return the bucket 18 to an upright position. It is well to note in this regard that utilization of this yieldable spring stop permits movement of the tilt jack to dead center. Even in this case, the spring compression will provide the impetus to return the bucket to a normal position until the tilt jack can apply enough leverage to continue return pivoting of the bucket.

It will be readily appreciated that the particular location of the spring stop means and the force which it must apply to provide the aforedescribed advantages will be de pendent upon the particular geometry and design of any particular loader mechanism. However, for any particular design, it is necessary only to position the stop means relative to the pivot point 16 and line of action of the tilt jack 36 between the pivot points 4% and 44 so that the spring and tilt jack forces provide the desired mutual opposition as the bucket 18 is dumped, whereby the potential energy stored within the yieldable stop will provide the initial impetus to return the bucket to an upright position even if it is pivoted to dead center in dumping.

As will be apparent, the yieldable stop means of this invention may be applied on any loader vehicle of the general type described, whether it be one which utilizes a tilt linkage as disclosed to automatically position the bucket as the booms are raised, or a commonly known straight parallelogram type of linkage to accomplish substantially this same purpose. Moreover, this invention may be practiced in conjunction with a loader in which the tilt linkage does not operate automatically, but must be manually actuated to position the bucket relative to the boom as the latter is lifted upwardly.

Moreover, where hydraulically actuated tilt linkages of the general type described are employed, it is immaterial whether or not the various elements thereof are in the positions shown in the drawing. For example, the tilt jack 36 and tilt control link 26 could be bodily reversed so that the tilt jack was connected between the vehicle and upper end of the intermediate lever while the rigid link was connected between the lower end of this lever and the material handling bucket. Furthermore, irrespective of which link is employed between the vehicle and the lever, it may be connected to either end of this lever while the other link is connected to the other end thereof and the bucket. Furthermore, other types of tilt linkages may be employed such as one in which the intermediate lever has one end pivotally connected to the bucket supporting boom arms 12 and the other end connected to the bucket by one link, while another link is connected intermediate the length of the lever and to the vehicle.

A preferred form of yieldable stop means has been shown and described for the purpose of explaining the significance of this invention. It will be readily apparent that the specific mechanical spring stop could be replaced by several equivalent structures such as an accumulator in which the movable element thereof is adapted for operative engagement with the stop plate 56, or a jack assembly in which the piston thereof could be moved to provide an adjustable sotp by a suitable fluid system which could be actuated automatically in response to elevation of the boom arms 12, or otherwise adjust such a stop to correspond to a particular boom height.

Having described the invention, it will be appreciated that the yieldable or adjustable stop means increases the versatility of loader mechanisms of this type by retaining the desired advantages of previous constructions, while eliminating disadvantages inherent therein by increasing the obtainable dump angle at higher lift positions and insuring proper operation of the mechanism in returning the material handling device to an upright position after dumping.

I claim:

1. A material handling attachment for a vehicle comprising, a supporting boom pivotally connected at one end to said vehicle, a material handling bucket pivotally connected to the other end of said boom, means for vertically adjusting said boom about its pivotal connection to said vehicle, tilt linkage means operable to pivot said bucket forwardly and rearwardly about its pivotal connec tion to said boom between material loading, carrying and dumping positions, said linkage means including, a lever pivotally connected to said boom, a first link pivotally connected to said lever and vehicle, a second link pivotally connected to said lever and to said bucket at a point spaced from the pivotal connection of the latter with said boom, one of said links being extensible and retractable, a stop bolt movably mounted on said boom in the path of and engageable with said bucket as the latter is pivoted to a dumping position, and spring means urging said stop bolt into engagement with said bucket and being progressively adjusted to greater extents as said boom is elevated.

2. A material handling attachment for a vehicle comprising, a supporting boom pivotally connected at one end to said vehicle, a material handling bucket pivotally connected to the other end of said boom, means for vertically adjusting said boom about its pivotal connection to said vehicle, tilt linkage means operable to pivot said bucket forwardly and rearwardly about its pivotal connection to said boom between material loading, carrying and dumping position, said linkage means including, a lever pivotally connected to said boom, a first link pivotally connected to said lever and vehicle, a second link pivotally connected to said lever and to said bucket at a point spaced from the pivotal connection of the latter with said boom, one of said links being extensible and retractable, and yieldable stop means mounted on said boom in the path of and engageable with said bucket as the latter is pivoted to a dumping position, said stop means yieldably opposing the thrust of said second link and being progressively adjusted to greater extents as said boom is elevated.

3. A material handling attachment for a vehicle comprising, a supporting boom pivotally connected at one end to said vehicle, a material handling bucket pivotally connected to the other end of said boom, means for vertically adjusting said boom about its pivotal connection to said vehicle, tilt linkage means operable to pivot said bucket forwardly and rearwardly about its pivotal con nection to said boom between material loading, carrying and dumping positions, said linkage means including a lever pivotally connected to said boom, a first link pivotally connected to said lever and vehicle, a second link pivotally connected to said lever and to said bucket at a point spaced from the pivotal connection of the latter with said boom, one of said links being extensible and retractable, and variably yieldable stop means mounted on said boom in the path of and engageable with said bucket as the latter is pivoted to a dumping position, said stop means yieldably opposing the thrust of said second link, said second link and the energy stored in said yieldable stop means being operable at any elevation of said boom to retract said bucket from a dumping position.

4. A material handling attachment for a vehicle comprising, a supporting boom pivotally connected at one end to said vehicle, a material handling bucket pivotally connected to the other end of said boom, means for vertically adjusting said boom about its pivotal connection to said vehicle, tilt linkage means operable to pivot said bucket forwardly and rearwardly about its pivotal connection to said boom between material loading, carrying and dumping positions, said linkage means including a lever pivotally connected to said boom, a first link pivotally connected to said lever and said vehicle, a second link pivotally connected to said lever and to said bucket at a point spaced above the pivotal connection of the latter with said boom, one of said links being extensible and retractable, and yieldable stop 'means mounted on said boom in the path of and engageable with said bucket as the latter is pivoted to a dumping position, said stop means being mounted to said boom beneath the pivotal connection thereto of said bucket and being progressively adjusted to greater extents as said boom is elevated upon engagement with said bucket to yieldably oppose the thrust of said second link, said second link and the energy stored in said yieldable stop means being operable at any elevation of said boom to retract said bucket from a dumping position.

References Cited in the file of this patent UNITED STATES PATENTS 2,301,241 Biedess Nov. 10, 1942 2,619,243 Biedess Nov. 25, 1952 2,711,256 Cutler June 21, 1955 2,711,257 Apel June 21, 1955 2,726,778 Hough et al Dec. 13, 1955 2,807,379 Pilch Sept. 24, 1957 2,846,097 Beyerstedt Aug. 5, 1958 FOREIGN PATENTS 679,830 Great Britain Sept. 24, 1952 

